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首页> 外文期刊>Journal of Applied Meteorology and Climatology >Observations of the Effects of Atmospheric Stability on Turbulence Statistics Deep within an Urban Street Canyon
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Observations of the Effects of Atmospheric Stability on Turbulence Statistics Deep within an Urban Street Canyon

机译：大气稳定性对城市街道峡谷深处湍流统计影响的观测

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Data obtained in downtown Oklahoma City, Oklahoma, during the Joint Urban 2003 atmospheric dispersion study have been analyzed to investigate the effects of upstream atmospheric stability on turbulence statistics in an urban core. The data presented include turbulent heat and momentum fluxes at various vertical and horizontal locations in the lower 30% of the street canyon. These data have been segregated into three broad stability classification regimes: stable (z/L > 0.2), neutral (—0.2 < zIL < 0.2), and unstable (z/L < -0.2) based on upstream measurements of the Monin-Obukhov length scale L. Most of the momentum-related turbulence statistics were insensitive to upstream atmospheric stability, while the energy-related statistics (potential temperatures and kinematic heat fluxes) were more sensitive. In particular, the local turbulence intensity inside the street canyon varied little with atmospheric stability but always had large magnitudes. Measurements of turbulent momentum fluxes indicate theexistence of regions of upward transport of high horizontal momentum fluid near the ground that is associated with low-level jet structures for all stabilities. The turbulent kinetic energy normalized by a local shear stress velocity collapses the datawell and shows a clear repeatable pattern that appears to be stability invariant. The magnitude of the normalized turbulent kinetic energy increases rapidly as the ground is approached. This behavior is a result of a much more rapid drop in the correlation between the horizontal and vertical velocities than in the velocity variances. This lack of correlation in the turbulent momentum fluxes is consistent with previous work in the literature. It was also observed that the mean potential temperatures almost always decrease with increasing height in the street canyon and that the vertical heat fluxes are always positive regardless of upstream atmospheric stability. In addition, mean potential temperature profiles are slightly more unstable during the unstable periods than during the neutral or stable periods. The magnitudes of all three components of the heat flux and the variability of the heat fluxes decrease with increasing atmospheric stability. In addition, the cross-canyon and along-canyon heat fluxes are as large as the vertical component of the heat fluxes in the lower portion of the canyon.
机译：在2003年“联合城市”大气扩散研究期间，分析了在俄克拉荷马州俄克拉荷马市市区获得的数据，以研究上游大气稳定性对城市核心湍流统计的影响。呈现的数据包括街道峡谷下30％处各个垂直和水平位置的湍流和动量通量。根据莫宁-奥布霍夫（Monin-Obukhov）的上游测量结果，这些数据已分为三个广泛的稳定性分类体系：稳定（z / L> 0.2），中性（-0.2

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